Two well-known glass fiber manufacturing methods are known as the rotary method and the flame blown method. Another well-known and widely used method is the CAT method, which is a modification of the rotary method. Manufacturing glass by these methods requires heating glass compositions past their melting temperatures into a working temperature range. Typical glass compositions used in making glass fibers have melting temperatures of about 2700° F. (about 1482° C.) and working temperatures (about 1427° C.). Existing compositions have relatively narrow working ranges, making the forming of glass fibers of desirable diameters and lengths difficult because it is difficult to maintain the glass compositions in the workable range. Additionally, the relatively high melting temperatures require large amounts of energy to melt the compositions, which can be very costly.
In addition, typical glass compositions used for making glass fibers have liquidus temperatures of about 1800° F. (about 982° C.). The liquidus temperature of typical compositions used for making glass fibers limits the useful life of fiberization equipment due to the high temperatures at which the equipment must operate. This is especially true when a spinner disc is employed in the fiberization equipment. A glass composition having a relatively low liquidus temperature also is useful for reducing or preventing crystallization of the glass during the fiberization process.
Glass fibers are used in a variety of applications. For example, glass fibers are used in several manners in batteries. Glass fibers are typically used as a separator that is preferably inserted between negative and positive plates of the battery. In addition, glass fibers are used as a part of a modified material mixed with a paste on the negative or positive plates of a battery. Further, glass fibers are used as a pasting paper that is applied to the surface of the plates to reduce the liberation of lead dust during manufacture.
Glass fibers tend to become brittle in humid environments, leach favorable and unfavorable components, and are unstable in acidic and/or alkaline environments. These characteristics of certain glass fibers can limit their usefulness in applications such as battery separators or filters. Ion leaching, for example, is a glass fiber surface phenomenon. The amount of ions lost from a glass fiber is proportional to the exposed surface area. Surface area considerations are typically greatest for glass fibers having diameters of less than about 5–7 μm. In some glass fibers certain metal oxide impurities (e.g., platinum oxide, iron oxide) leach out of the fibers and have a detrimental effect on the life of the battery.
Known glass compositions do not meet desired characteristics.